WCDMA ( 3G ) Channels "Detailed" Chapter Two/Three

WCDMA ( 3G ) Channels

Channel Mapping

·       The data can be sent through logical layer via different channels in the transport layer.
·       And also one transport channel can be sent via different physical channels.
·       These selection of channels in the transport and physical layer depends on the data itself and radio resource management and its parameters.

WCDMA DOWNLINK (FDD)

Burst Types – Dedicated Physical Channel

·       There are four different types of bursts
·       All contains two data fields, midamble and GP.
·       Length of each is different in each bursts.
·       The no. of data symbol depends on SF or burst type.

Burst Type – I

·       This burst type used for both Uplink and Downlink
·       It has larger training sequence due to longer midamble field
·       Data field has 976 chips long, no. of symbol depends on the SF
·       Midamble is 512 chips long and GP is 96 chips period.

Burst Type – II

·       This burst type used for both Uplink and Downlink
·       It has shorter training sequence due to longer midamble field
·       Data field has 1104 chips long, no. of symbol depends on the SF
·       Midamble is 256 chips long and GP is 96 chips period.

Burst Type – III

·       This burst type used for Uplink only
·       It has longer guard period suitable for initial access or accss to new cell after handover
·       Data field has 976 and 880 chips long, no. of symbol depends on the SF
·       Midamble is 512 chips long and GP is 192 chips period.

Burst Type – IV

·       This burst type used for downlink MBSFN
·       It has longer guard period suitable for initial access or accss to new cell after handover
·       It has two data fiels each of 1056 chips long, no. of symbol depends on the SF
·       Midamble is 320 chips long and GP is 128 chips period.

TPC

1.     Transmission of TPC burst is done in the data parts of traffic burst.
2.     Data in TPC is always transmit at SF 32 irrespective SF of user data
TPC information is to be transmitted immediately after the midamble
Shall be transmitted with same channelization code and timeslot of TFCI

TFCI

·       Transmission of TFCI is done in the data parts of the respective physical channel.
·       In Downlink the TFCI code word bit and data bit subjected to the same spreading procedure
·       In Uplink, independent to the SF of data bits TFCI code is applied with SF 32
·       TFCI is code to be transmitted directly adjacent to the midamble

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